Is 121 Prime?

Check if 121 is a prime number. A prime number is only divisible by 1 and itself.

Result: ✗ NO — 121 is NOT a prime number

Step-by-Step Solution

Step 1 What is a Prime Number?

A prime number is a natural number greater than 1 that has exactly two factors: 1 and itself.

To check if 121 is prime, we need to verify that no number from 2 to √121 divides it evenly.

Step 2 Determine Testing Range

Since 121 is odd, we only need to check odd divisors.

We only need to test up to √121 ≈ 11.00, which rounds down to 11.

If 121 has a factor larger than √121, it must also have a corresponding factor smaller than √121.

Step 3 Test Odd Divisors

Testing: 3, 5, 7, ... up to 11

121 ÷ 3 = 40 remainder 1

121 ÷ 5 = 24 remainder 1

121 ÷ 7 = 17 remainder 2

121 ÷ 9 = 13 remainder 4

121 ÷ 11 = 11 (no remainder!)

We found that 11 divides 121 evenly!

Step 4 Conclusion

121 = 11 × 11

Since 121 has factors other than 1 and itself, 121 is NOT a prime number.